This application is a request for an R03 award through the NIDA Small Grants Program to evaluate the acceptability and feasibility of rapid testing for HIV among adolescent and young adult substance users 16-25 years of age. Dr. Pugatch, the principal investigator, is an Assistant Professor of Pediatrics and Medicine at the Brown Medical School. He is currently in his final year of a NIDA mentored career development award. Young substance users ages 16-25 are at high-risk for HIV disease due to both needle sharing and sharing of "works" associated with injection drug use, and risky sexual behaviors. Two populations of adolescents with high rates of active substance use are proposed for this study: 1) adolescents at an in-patient, short-term drug treatment facility and 2) homeless youth engaged in social services. The investigators have considerable experience conducting adolescent HIV testing research in adolescents with drug abuse. Follow-up for HIV test results is a problem nationwide, and new technology now makes it possible to do rapid HIV testing and make immediate results available. OraQuick(r) is a new rapid HIV test approved by the FDA and can easily be administered outside of a clinical setting. Rapid tests have not yet been field tested in at-risk adolescent populations. Three hundred youth between the ages 16-25 will complete a brief face-to-face risk assessment. The study will be conducted in two settings, one being a short-term inpatient drug treatment facility and the other a community outreach program for the homeless (75 males and 75 females of the same age group at each site). After completion of the questionnaire, participants will be offered the rapid finger-stick HIV test using OraQuick(r). A standard protocol will be used for HIV pre- and post-test counseling. Results will be delivered within one hour. Participants who test positive will be given a preliminary positive result, will be re-tested by confirmatory Western Blot, and immediately linked to medical care. Acceptability of rapid testing, reasons for refusal, satisfaction with the rapid counseling and testing protocol and proportion of testers who receive results will be analyzed by site, by gender at each site, and by the acuity of the participants' risk. These results will provide preliminary data for a future randomized trial to compare same-day rapid testing versus standard testing with one week follow-up for testing acceptance, receiving results, and risk reduction.